Cognitive Decline Increases Risk of Natural Cause Mortality in Schizophrenia, New Study Reveals

Schizophrenia is a complex and chronic mental health disorder characterized by disruptions in thought processes, perceptions, and emotional responsiveness. It is linked to increased premature mortality, primarily due to natural causes. Recent findings indicate that reduced cognitive functioning, a known risk factor for mortality in the general population, also plays a significant role in this heightened risk. Nevertheless, there has been a limited number of prospective studies addressing this issue in individuals with schizophrenia.

To fill this knowledge gap, Faith Dickerson, Stanley Research Program, Sheppard Pratt, Baltimore, Maryland, and colleagues aimed to investigate whether lower cognitive functioning is a risk factor for natural cause mortality in schizophrenia.

For this purpose, the researchers conducted a prospective cohort study involving individuals with schizophrenia or schizoaffective disorder enrolled between February 1, 1999, and December 31, 2022, at a nonprofit psychiatric system in Baltimore, Maryland. Participants underwent evaluations using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and other clinical measures.

The study focused on natural cause mortality as the primary outcome. To assess this, the researchers analyzed the associations between cognitive function, obesity, tobacco smoking, and various medical conditions with natural cause mortality. They employed Cox proportional hazards regression models to determine the impact of these factors on mortality rates.

The researchers reported the following findings:

• Of the 844 participants enrolled (mean age, 39.6 years; 63.2% males), 158 died of natural causes during a median follow-up of 14.4 years.
• The most significant factor associated with mortality was lower cognitive functioning as measured by the RBANS.
• Additional factors independently associated with mortality included the diagnosis of an autoimmune disorder (hazard ratio [HR], 2.86), tobacco smoking (HR, 2.26), diagnosis of chronic obstructive pulmonary disease (HR, 3.31), body mass index as a continuous variable (HR, 1.06), diagnosis of a cardiac rhythm disorder (HR, 2.56), and being divorced or separated (HR, 1.80).
• An RBANS score below the 50th percentile displayed a joint association with being a smoker, having an elevated body mass index, and having a diagnosis of an autoimmune or cardiac rhythm disorder.

In the study, reduced cognitive functioning was identified as a risk factor for natural cause mortality among individuals with schizophrenia.

"These findings indicate that enhancing cognitive functioning should be a key focus for individuals with schizophrenia, particularly those who also have additional risk factors for mortality," the researchers concluded.

Reference:

Dickerson F, Khan S, Origoni A, et al. Risk Factors for Natural Cause Mortality in Schizophrenia. JAMA Netw Open. 2024;7(9):e2432401. doi:10.1001/jamanetworkopen.2024.32401